[release/2.3] istio: Bump chart to v1.6.7

[gracedo]

What type of PR is this?

Bug

What this PR does/ why we need it:

Backport #481 which removes a servicemonitor in istio that was pulling in bad targets.

Which issue(s) this PR fixes:

https://jira.d2iq.com/browse/D2IQ-70603
https://jira.d2iq.com/browse/COPS-6403

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

istio: The "kubernetes-service-monitor" service monitor has been removed.

Checklist

• The commit message explains the changes and why are needed.
• The code builds and passes lint/style checks locally.
• The relevant subset of integration tests pass locally.
• The core changes are covered by tests.
• The documentation is updated where needed.

[shaneutt]

Needs a couple of things before we move forward:

1. fixes for CI issues
2. we need to turn the Istio test group back on, it's currently disabled (commented out) in test/groups.yaml.

[shaneutt]

✔️ once CI is happy, given that we don't have any automated tests for the service monitors we should test manually that those are functional before merging.

[gracedo]

Spun up a cluster using this branch of kba and verified that the kubernetes-service-monitor is no longer deployed with istio, and there are no longer enough unhealthy targets

$ k get servicemonitors -nistio-system
NAME                      AGE
envoy-stats-monitor       10m
kubernetes-pods-monitor   10m